Polyphenylene sulfide (hereinafter abbreviated as PPS) resins have suitable properties as engineering plastics such as excellent heat resistance, barrier properties, chemicals resistance, electric insulation and wet heat resistance, and are mainly injection-molded or extrusion-molded for use as various electric/electronic parts, mechanical parts, automobile parts, etc.
However, since PPS resins are low in toughness compared with other engineering plastics such as nylons and PBT, they are limited in application and are strongly desired to be enhanced in toughness.
As methods for enhancing the toughness of a PPS resin, methods of mixing a high toughness material such as a polyamide resin with a PPS resin have been examined. For example, a method of mixing a polyamide and an organic silane compound with a PPS resin, a method of mixing a polyamide and an epoxy group-containing copolymer with a PPS resin, etc. are disclosed. However, the toughness levels achieved by these methods were not satisfactory. Further, many compositions obtained by mixing a polyamide with PPS are known. For example, disclosed are a composition with polyamide 11 or 12 with an average particle size of 1 μm or less dispersed in PPS, a composition comprising PPS, polyamide and epoxy resin, a composition comprising PPS and copolyamide, etc. However, dispersing a polyamide into PPS as ultrafine particles of less than 500 nm is not described at all. It would therefore be advantageous to obtain a polyphenylene sulfide resin composition very excellent in toughness.